Environmental pressures at the top of the Earth produce evolutionary impacts

By Henry P. Huntington

Charles Darwin’s “On the Origin of Species” led, among other things, to scientific and public acceptance of the idea that species, including ours, can and do change over time. The mechanisms of change—competition, selection, adaptation—operate today, most visibly in surroundings that also are rapidly changing. Arctic species and societies at the top of the Earth’s Northern Hemisphere, for example, are under immense environmental pressures from global climate change that result in both animals and people making observable, behavioral adjustments for survival. The evolutionary impacts on both are worth noting.

The defining feature of the Arctic marine environment is its sea ice, which is currently threatened by rising regional temperatures. Available evidence suggests the Arctic has had year-round ice for the past 800,000 years, long enough for many species to evolve in and adapt to its presence. Bowhead whales are capable of breaking ice up to two feet thick in order to make breathing holes. Beluga whales navigate through hundreds of miles of pack ice without difficulty. Seals use ice to rest and use the snow that drifts by pressure ridges to make dens for bearing their pups. Polar bears do not hibernate like their brown bear cousins, but roam the ice throughout the winter, hunting seals.

Within the past 40,000 years, humans have moved into the Arctic in increasing numbers, perhaps attracted by opportunity, perhaps given a push from neighbors. The existing animal population made it possible for them to adapt to the sea ice environment, establish Arctic cultures and even thrive despite the climate, the prolonged winter darkness and the isolation. For many Arctic peoples, these marine resources—marine mammals in particular— have been a primary source of nutritional and cultural sustenance.

But new challenges have arisen in the modern era for hunting cultures, such as the Inuit or Eskimo peoples, who have a long, historical relationship with Arctic animals. Among these, climate change threatens to force some Arctic species away from their usual ranges, out of reach of coastal communities. As Arctic species migrate away, some subarctic species may move north to fill the gap. Alternatively, we may also see some Arctic species adapt and evolve.

Early evidence for these changes has already been observed. In 2007, sea ice retreated far from shallow-water feeding areas in the Chukchi Sea, and walrus hauled out on land in northern Alaska for the first time, an example of potential new behavioral adaptations. In Canada, polar bears have interbred with brown bears, raising the possibility of a new species that could perhaps survive better in the increasingly ice-free Arctic.

Cultural responses of people dependant on these animals will be determined in large part by the environment, but that response will be heavily mediated through social mechanisms such as regulation, culture, perception and technology. So, while the evolution of new species may occur, the evolution of traditional arctic cultures may also take place.

Arctic societies have adapted to both slow and rapid changes in the past, and will again adapt to changes as they occur. In doing so, those societies will lose some cultural opportunities and gain new ones. Arctic species may adapt, may evolve or may go extinct.

As the prospect of an ice-free Arctic becomes ever more plausible, we should recognize that such a change means losing the true Arctic, leaving us with a subarctic that stretches to the North Pole. What that subarctic will look like remains to be seen—for people, for animals and for ecosystems. This giant, though unintended, experiment will show how some of Darwin’s ideas play out, and perhaps it will illuminate the differences between natural selection in the biological world and cultural adaptation among humans.

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Henry Huntington is an independent researcher living in Eagle River, Alaska. His work examines relationships between people and their environment, primarily in Alaska and other Arctic locations. He documents traditional knowledge of Arctic peoples, looks at the impacts of climate change in the region and assesses likely impacts to Arctic marine mammals from various threats including climate change and industrialization. He writes about his research for dozens of scientific journals and for general audiences. The National Science Foundation supports his research on human responses to changing climate in Alaska and Nepal.

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